Explanation: Why is Io green at night? In this just-released nighttime picture
of Jupiter's moon Io,
the red spots clearly show Io's
current volcanically active regions.
But what is causing the global green sheen? This telling picture
was taken by the automated Galileo spacecraft currently orbiting Jupiter
while Io was in Jupiter's shadow. One hypothesis is that the green
glow is caused by a different type of aurora
resulting from high-energy particles interacting with Io's volcanic plumes.
**Palette:** *nblofi*
Original
